The Internet can provide a source of revenue for many businesses. However, the Internet can also pose risks as dishonest individuals exploit security vulnerabilities. These attackers can be difficult to identify, because they may co-opt other computers using software robot applications. As attackers generate networks of co-opted machines (“botnets”), they can do greater damage. For example, a botnet may be used to replicate a proprietary database by continuously submitting search queries to a search engine communicating with the proprietary database and by recording all search results returned by the search engine interface.
Businesses that operate such proprietary databases may wish to distinguish legitimate users from non-legitimate users. Nonetheless, previous techniques often present inconvenience to legitimate users, particularly for public search engines (i.e., those with no user name or password requirement). Further, techniques such as blacklisting may become impractical as the number of users increases. Hence, there is a need for an improved system and method of processing database search queries.